A MIMO (Multiple Input Multiple Output) OFDM (Orthogonal Frequency Division Multiplexing) system such as an LTE (Long Term Evolution) or the like standardized by the 3GPP (3rd Generation Partnership Project) is attracting attention as a next generation communication system.
In the MIMO-OFDM system, a transmission rank most suitable for data transmission is estimated at a receiver side, the estimated transmission rank is fed back to a transmitter, and data is transmitted at a transmitter side according to the transmission rank fed back from the receiver side. As a result, maximum throughput at the receiver can be obtained.
For example, patent document 1 is a technical literature in which a technical content for estimating the above mentioned transmission rank is disclosed.
In patent document 1, a technique with which a communication capacity between a transmitter and a receiver is calculated for all the ranks and the rank of which the maximum communication capacity can be obtained is selected is disclosed.